Piston pump

ABSTRACT

In a piston pump ( 1 ), in particular for pressure medium delivery in slip-controlled hydraulic brake systems, including a suction valve ( 82 ) and a delivery valve ( 81 ), external preassembly and possibilities of external testing of the delivery and suction valves ( 81,82 ) result from providing the suction valve ( 82 ) and the delivery valve ( 81 ) within a component ( 8 ) which can be handled independently. The component ( 8 ) preferably includes a delivery valve ( 81 ) provided radially to the center line and a valve seat member ( 70 ), with a valve body ( 95 ) of the delivery valve ( 81 ) being prestressed by a tongue ( 121 ) of a clamp ( 120 ), placed onto the valve seat member ( 70 ), against a valve seat ( 96 ) formed within the valve seat member ( 70 ).

The present invention relates to a piston pump, in particular to apiston pump used in slip-controlled hydraulic brake systems as definedby the preamble of claim 1.

Such a piston pump, e.g., is known from EP 0 631 050 B1. The piston pumpaccording to this prior art includes a delivery valve and a suctionvalve, both arranged within a pump housing so that they are separatefrom each other in terms of location and construction. Moreover, theknown delivery and suction valves are assembled within the pump housingone after the other in terms of time and, once assembled, it is nolonger possible to test them without a major effort. However, beforeassembly, it is likewise not readily possible to perform an optimum testof these valves since in such a case the assembled conditions would haveto be simulated as accurately as possible and since the valves could betested only separately.

A ball-type-design delivery valve is known particularly in the contextof the examples of embodiments of a known piston pump as disclosed inFIGS. 11 through 19 of EP 0631 050 B1. There, a valve body having thedesign of a ball is prestressed, with a ring means being used, against avalve seat designed as radial bore. This known delivery valve hasdisadvantages in that the assembly of the ring means on the valve seatmember of the delivery valve requires a major effort and in that itstype of fastening is not particularly stable. In this known arrangementit is moreover possible that the ring means twists or is displaced and,thus, the ball slips out of its valve seat or there is a change in thepre-stressing force.

It is an object of the present invention to avoid the disadvantages ofprior art and, in particular, to provide a piston pump enabling both thedelivery valve and the suction valve to be preassembled and testedbefore being assembled into a pump housing, i.e., enabling externalpreassembly and testing.

This inventive task is solved in a generic piston pump in that thedelivery valve and the suction valve are provided on a component whichcan be handled independently.

An essential advantage of the present invention consists in that theinventive design of the delivery and suction valves provides a valvecartridge unit allowing external preassembly and testing. Moreover, itis possible to reduce the number of parts used as well as the rejects ofdefective units and, consequently, the cost of manufacture. A furtheradvantage of this invention is the fact that the time needed forassembling the inventive piston pump is considerably reduced whichlikewise means a drop in costs. The constructional combination ofdelivery valve and suction valve, moreover, results both in space beingsaved and in an optimum utilization of the space available for thevalves within the pump housing. Finally, the constructional combinationof delivery and suction valves permits a simple recessing of the valveseat member as no separate valves have to be accommodated within thepump body.

In a preferred embodiment of this invention, the component is fastenedwithin the pump housing by means of caulking or clinching. This type offastening is beneficial in terms of cost and enables pressure-tightassembly of the component within the pump housing. Further, thisrestricts the possibilities of inexpert manipulation of the brakesystem.

So as to reduce the number of parts required for assembling thecomponent it is an advantage to provide one spring element for jointlyprestressing the delivery valve and the suction valve. This springelement may have the design of a compression spring or of a tensionspring.

Advantageously, the component includes a valve seat member wherein thereis provided a valve seat for the delivery valve and a valve seat for thesuction valve. This results in an especially space-and-material-savingdesign of the component of the inventive piston pump.

According to a further embodiment of this invention, the piston pumpincludes a cup-shaped pump piston, with the component including anaxially projecting gudgeon portion wherethrough the cup-shaped piston isguided. An advantage of this embodiment is the fact that the pumphousing does not have to undergo hardening or anodizing.

Advantageously this component includes a valve seat member with an axialrecess formed on one of its front sides for guiding the pump piston ofthe piston pump therein or rather for having it plunge into this recess.Preferably, the suction valve is arranged on the other, opposite frontside of the valve seat member essentially axially to the center line ofthe valve seat member while the delivery valve is arranged essentiallyradially to said line. This arrangement is particularly space-saving asthe pump piston, together with its resetting spring, can plunge into therecess whereby the length of the bore wherein the pump piston moves isshortened.

According to a variant of this invention, the suction valve includes acompression spring secured by means of a bowl-type spring retainerprovided with a stop formed thereon for the valve body of the suctionvalve and further including means for guiding the compression spring andmeans for guiding a piston return spring serving to reset the piston.The bowl-type spring retainer thus combines a plurality of differentfunctions which means a saving of space and material. Further, thedesign of the stop for the suction valve body prevents the suction valvebody from becoming jammed within the bowl-type spring retainer.

Advantageously, the means for guiding the compression spring and themeans for guiding the piston return spring form a cup-shaped portion ofthe bowl-type spring retainer, with the compression spring being guidedon the inside of the cup-shaped portion and the piston return springbeing guided on the outside of the cup-shaped portion. The stop of thebowl-type spring retainer preferably serves as an internal guideway forthe compression spring. This is particularly beneficial since thebowl-type spring retainer, due to its function as a retaining cage forthe suction valve body, is anyway concave, i.e., provided with acup-shaped portion and since, further, the bowl-type spring retaineranyway includes a stop in order to prevent the suction valve closuremember from becoming jammed within the bowl-type spring retainer.

In accordance with this invention, further provided is a delivery valvewith a valve seat member, in particular for a piston pump, with a valvebody of the delivery valve being prestressed by a clamping element,mountable to the valve seat member, against a valve seat formed withinthe valve seat member. Particularly advantageous is the fact that theclamping element includes a tongue which is formed thereon andprestresses the valve body against the valve seat. The use of thisinventive tongue instead of, for instance, a helical spring is possiblebecause the opening pressure of the delivery valve does not have to beadjusted as accurately as that of the suction valve. It is thus possibleto substitute the helical spring in the delivery valve for a tongueprovided on the clamping element. The tongue urges the valve bodyperpendicularly onto the valve seat while simultaneously fixing thevalve body axially and radially. Fixation of the valve body may even beimproved by means of a bore which can additionally be provided withinthe tongue and at least partially is engaged by the valve body. Further,the arrangement of the tongue on the clamping element also offers theadvantage of adjustability of the resiliency over the length of thetongue, even with a predetermined construction of the valve body.Finally, the arrangement of the tongue within the clamping elementoffers sufficient surface contact between the clamping element and thevalve seat member, namely by means of the surfaces adjoining the tongue,whereby the clamping element can much better be fastened on the valveseat member.

Preferably, the clamping element has a tab, provided perpendicularly tothe tongue, for fastening the clamping element on the valve seat member.Thus it is possible to a great extent to prevent the clamping elementfrom twisting and getting loose.

In a preferred embodiment of this invention, the clamping elementincludes at least one tab, provided parallel to the tongue, forfastening the clamping element in a valve seat member recess serving toreceive the valve body. This does not require a separate bore in thevalve seat member for fastening the tab.

If the clamping element is dimensioned considerably wider than the valvebody, the larger contact surface between clamping element and valve seatmember results in an improved fastening of the clamping element on thevalve seat member because of only the tension of the clamping element.

So as to facilitate the radial slipping-on of the clamping element ontothe valve seat member the cross sides of the clamping element preferablyinclude end portions arched outwards. Slipping-on, however, may also bedone axially, starting from an end portion of the valve seat member.

In the following, this invention as well as further advantages andembodiments of the same will be explained with reference to thedrawings. Like or similar reference numerals in the drawings designatelike or corresponding elements. Please note that the followingdescription of the Figures particularly will deal with the differencesbetween the various examples of embodiments. Therefore, the descriptiongenerally will refer to examples of embodiments described before as faras features are concerned they have in common. In the drawings,

FIG. 1 is a view of a longitudinal section of a first example of anembodiment of the present invention;

FIG. 2 is a view of a longitudinal section of a second example of anembodiment of the present invention;

FIG. 3 is a view of a longitudinal section of a third example of anembodiment of the present invention;

FIG. 4 is a view of a longitudinal section of a fourth example of anembodiment of the present invention;

FIG. 5 is a view of a longitudinal section of a fifth example of anembodiment of the present invention;

FIG. 6 is a view of a longitudinal section of a sixth example of anembodiment of the present invention;

FIG. 7 is a view of a longitudinal section of a seventh example of anembodiment of the present invention;

FIG. 8 is a view of a longitudinal section of an eighth example of anembodiment of the present invention;

FIG. 9 is a cross-sectional view of an inventive delivery valve alongline IX—IX of FIG. 8;

FIG. 10 is a view of a longitudinal section of a ninth example of anembodiment of the present invention;

FIG. 11 is a cross-sectional view of a further embodiment of aninventive delivery valve along line XI—XI of FIG. 10;

FIG. 12 is a view of a longitudinal section of a tenth example of anembodiment of the present invention;

FIG. 13 is a cross-sectional view of a further embodiment of aninventive delivery valve along line XIII—XIII of FIG. 12;

FIG. 14 is a view of a longitudinal section of an eleventh example of anembodiment of the present invention;

FIG. 15 is a perspective view of a retaining bow for being used on theinventive delivery valve as per FIG. 14; and

FIG. 16 is a cross-sectional view along line XVI—XVI of FIG. 14 of apreferred embodiment of an inventive delivery valve.

FIG. 1 represents a view of a longitudinal section of a first example ofan embodiment of an inventive hydraulic pump or rather piston pump 1preferably used in an ABS (Anti-lock Braking System), TCS (TractionControl System) or ESP (Electronic Stability Program) system of acontrolled vehicle brake apparatus. Within its housing 2, the hydraulicpump 1 constructed as a piston pump includes an eccentric 4 driven by adrive shaft 3. In this example of an embodiment, a pump piston 6 isconnected with a non-illustrated second pump piston via a coupling ring5 and is thus in contact with eccentric 4. During the rotation of thedrive shaft 3, the pump piston 6 is linearly reciprocating within astepped bore 7 of pump housing 2. A component 8 such as a cartridgeseals the end of stepped bore 7, lying opposite eccentric 4, in apressure-tight manner. Cartridge 8 is fastened within the pump housing 2by means of, e.g., caulking or clinching. On the outside of thecartridge or rather component 8, an outwards bulging cap 9 forms apressure damping chamber 10. According to this invention, cartridge 8includes a pressure-controlled delivery valve 11 and apressure-controlled suction valve 12. The valve cartridge 8 may bepreassembled and tested outside the valve block or rather outside pumphousing 2. Delivery valve 11 includes a valve seat member 13. Valve seatmember 13 includes a central bore 14 the center line M of whichcoincides with the longitudinal axis of pump piston 6. As seen from theoutside to the inside, central bore 14 of the valve seat member 13includes three stepped sections 15, 16, and 17. The diameter of theoutsidemost section 15 is larger than the diameter of the mid-section 16while the latter, on its part, is larger than that of the innermostsection 17. The valve seat member 13 includes an outer end portion 18and an opposite, sleeve-type, inner end portion 19. The stepped sections15, 16 and part of stepped section 17 of bore 14 are formed within endportion 18. The sleeve-type end portion 19 of valve seat member 13likewise includes part of stepped section 17 of bore 14. The end portion18 of valve seat member 13 includes an annular channel 20 formed alongits outside periphery and leading to a non-illustrated low-pressureaccumulator via a schematically indicated bore 21. When the suctionvalve 12 is open a bore 22 extending obliquely to line M connectsannular channel 20 with a chamber 23 confined by piston 6, with endportion 19 of valve seat member 13 projecting into chamber 23. The endof end portion 19 of the valve seat member 13 which faces piston 6 isbent outwards in order to receive a retaining ring 24 slipped onto endportion 19. A compression spring 25 supports itself on a step formed onthe retaining ring 24, on the one hand, and on a step formed on a valveelement 26 of suction valve 12, on the other hand. Valve element 26serves as closure member of suction valve 12. Compression spring 25prestresses valve element 26 against its seat, i.e., a front side of thevalve seat member 13 facing piston 6 and lying radially outside endportion 19. In this position of suction valve 12, chamber 23 does notcommunicate with the low-pressure accumulator. A step between sections16 and 17 of bore 14 forms a valve seat for a valve element of deliveryvalve 11. Said valve element preferably has the design of a ball 27.Ball 27 is prestressed by a compression spring 28 against its seat whilethe end of compression spring 28 which is opposite of ball 27 supportsitself on a plug 29 arranged within bore 14. Plug 29 includes a pinelement 30, projecting inside, for guiding compression spring 28. Theoutside diameter of pin element 30 approximately corresponds to theinside diameter of compression spring 28.

During the operation of the inventive hydraulic pump 1, the pressure ofbrake fluid is increased in chamber 23 in a delivery stroke phasewherein pump piston 6 moves to the right according to the view of FIG.1. To this end, a seal 31 is provided around the periphery of pumppiston 6. The pressurized brake fluid in chamber 23 now presses the ball27, against the prestress of compression spring 28, away from its seatwhereby pressurized brake fluid is transferred to a pressure mediumconsumer such as the wheel brakes. In a suction phase, while pump piston6 moves to the left according to the view of FIG. 1, delivery valve 11remains closed, i.e., under the action of compression spring 28 ball 27is pressed against its valve seat formed on the bordering surface ofsections 16 and 17. During this suction stroke phase, the relativepressure reduction of the brake fluid in pressure chamber 23 openssuction valve 12. Then, pressure medium is sucked into pressure chamber23 via the low-pressure accumulator, bore 21, annular channel 20 andbore 21 ¹).

FIG. 2 represents a view of a longitudinal section of a second exampleof an embodiment of the present invention. As distinguished from thefirst example of an embodiment of the present invention alreadydescribed in the context of FIG. 1, the example of an embodimentaccording to FIG. 2 features a different design of cartridge 8.According to the second example of an embodiment of the presentinvention represented in FIG. 2, suction valve 12 of cartridge 8 isdesigned as a ball-type valve just as delivery valve 11, with thearrangement of suction valve 12 within cartridge 8 approximately beingperpendicular to that of delivery valve 11. Cartridge 8 thereforeincludes a stepped radial bore 32 besides axial bore 14 provided fordelivery valve 11. A ball 33 serving as valve body and prestressed by acompression spring 34 against a step formed within radial bore 32 is theclosure member of suction valve 12.

FIG. 3 represents a view of a longitudinal section of a third example ofan embodiment of the present invention. In general, the design of thehydraulic pump 1 represented in FIG. 3 is similar to the design ofhydraulic pump 1 already described in the context of FIGS. 1 and 2.However, the main differences between the example of an embodiment ofthis invention, represented in FIG. 3, and those two first examples ofembodiments of this invention lie in the design of cartridge 8. Withincartridge 8, a delivery valve 41 and a suction valve 42 areconstructionally combined. Instead of a ball 27 (cf. FIGS. 1 and 2),delivery valve 41 includes as valve body a conical valve tappet 43preferably made of steel or plastic and prestressed by a tension spring44 against its valve seat, namely a central bore 45, within valve seatmember 46 of delivery valve 41. One end of tension spring 44 is fastenedto a fastening eyelet or the like of valve tappet 43. Via a retainingelement 47, the opposite end of tension spring 44 is connected with anessentially conical (lower half of drawing) or plane (upper half ofdrawing) closure member 48 of suction valve 42. Closure member 48 is aring made of plastic. In the third example of an embodiment of thepresent invention represented in FIG. 3, thus, only one sole springmeans, namely tension spring 44, is provided for prestressing the valvetappet 43 of delivery valve 41 and the closure member 48 of suctionvalve 42.

Referring to FIG. 4, a fourth example of an embodiment of the presentinvention is described. The fourth example of an embodiment of thepresent invention, represented by a view of a longitudinal section, ingeneral is similar to the third example of an embodiment of thisinvention represented in FIG. 3. However, the design of the valves,namely of delivery valve 41 and suction valve 42, combined within valvecartridge 8 is different from the above described variants of thisinvention. Delivery valve 41 includes a valve seat member 46 with acentral bore 45 serving on its outside as a seat for a valve tappet 53.Valve tappet 53, preferably made of steel or plastic, includes a pinportion 54 and two end portions 55, 56 conically flaring outwards. Endportion 55 serves as valve body for delivery valve 41 (cf. valve tappet43 as per FIG. 3), while end portion 56 serves to support the valvetappet 53 within a central bore 57 of a retaining plate 58. Anespecially inwards-bent outside-periphery portion 59 of retaining plate58 is provided for the support of a compression spring 60 designed as ahelical spring. Suction valve 42 has an annular closure member 61 madeof plastic. Closure member 61 comprises a central bore 62 wherein valvetappet 53 moves. On its front side facing pump piston 6, closure member61 of suction valve 42 includes an annular step 63 serving to supportand guide compression spring 60. On its front side averted from pumppiston 6, closure member 61 is conical or plane and abuts on a matingvalve seat, formed within the valve seat member 46, when suction valve42 is closed. Compression spring 60 presses closure member 61 of suctionvalve 42 against its seat in order to prestress suction valve 42 intothe closed condition and further presses end portion 55 of valve tappet53 against its seat in order to prestress delivery valve 41 into itsclosed condition. The pump piston 6 moving to the right according to theview of FIG. 4 during a delivery stroke, the pressurized brake fluidopens delivery valve 41. In doing so, the hydraulic pressure of thebrake fluid acts against the prestressing force of the compressionspring 60. The pump piston 6 moving to the left according to the view ofFIG. 4 during a suction stroke phase, the relative vacuum forming withinchamber 64 ensures the opening of the suction valve 42 against theprestressing force of compression spring 60.

Please note that the respectively third and fourth examples ofembodiments of the present invention represented in FIGS. 3 and 4 areadvantageous in that only one spring element is required for both thedelivery valve 41 and the suction valve 42. As compared with theexamples of embodiments as per FIGS. 1 and 2, this saves one spring sothat the (valve) cartridge 8 in accordance with the third and fourthexamples of embodiments includes only 5 elements, namely valve seatmember 46, closure member 48 or 61, respectively, retaining element 47or retaining plate 58, respectively, tension spring 44 or compressionspring 60, respectively, and valve tappet 43 or 53, respectively.

FIG. 5 represents a view of a longitudinal section of a fifth example ofan embodiment of the present invention. The design of valve cartridge 8in accordance with FIG. 5 in general is similar to the design of valvecartridge 8 as per the second example of an embodiment described in thecontext of FIG. 2. This is particularly true in so far as cartridge 8includes an axial delivery valve 11 on one end portion and a suctionvalve 12 provided radially thereto. What is different from the exampleof an embodiment of FIG. 2 is that cartridge 8 includes a valve seatmember 70 provided with a gudgeon 71 preferably made of steel and formedinwards or rather towards eccentric 4. A peripheral groove 72 isprovided on gudgeon 71 and serves to receive a gasket 73. Designed onthe front side of gudgeon 71, in FIG. 5, is a stepped bore 74 serving toreceive a compression spring or rather a piston return spring 75 andforming a chamber 76. The pump piston driven by the eccentric 4 isdesigned as cup-shaped piston 77. The cup-shaped piston 77 includes abore 78 the inside diameter of which approximately corresponds to theoutside diameter of gudgeon 71. Designed on a bottom section of bore 78is an axial projection 79 the outside diameter of which essentiallycorresponds to the inside diameter of compression spring 75. The outsidediameter of projection 79 slightly tapers outwards so as to facilitatethe assembly of compression spring 75. The cup-shaped piston 77 ispreferably made of steel and, e.g., may be an extruded part. This allowsthe play between the cup-shaped piston 77 and gudgeon 71 to be kept verysmall because of almost the same coefficients of expansion. Besides,there is no further need for the housing 2 to be anodized or hardened.This prevents any pollution caused by clinching in or rather by caulkingthe valves and caps. It is noticed from FIG. 5 that compression spring75 is arranged within the cup-shaped piston 77 and, more precisely,within a chamber 76 formed by the cup-shaped piston 77 and gudgeon 71.

Regarding the sixth example of an embodiment of the present inventionrepresented in FIG. 6, what is different from the example of anembodiment of the present invention represented in FIG. 5 is thatcompression spring 75 serving to reset the cup-shaped piston 77 issupported on a step formed on the outside of the cup-shaped piston 77.On its opposite side, compression spring 75 is supported and guided on astep of valve seat member 70, this step being formed by the bottom ofgudgeon 71. Also serving as chamber or rather as compression chamber 76in this example of an embodiment according to FIG. 6 is, inter alia, anaxial bore 80 within gudgeon 71. Please note that, as contrasted withthe examples of embodiments represented in FIGS. 1 through 4, theexamples of embodiments of the present invention represented in FIGS. 5and 6 are provided with compression spring 75 for resetting thecup-shaped piston 77 instead of with coupling ring 5.

A seventh example of an embodiment of the present invention isschematically represented in FIG. 7. The cartridge 8 represented in FIG.7 includes a delivery valve 81 and a suction valve 82. The suction valve82 designed in the centre of the valve seat member includes a valve bodywhich has the design of a ball 83 and which, in the closed condition ofsuction valve 82, abuts on a valve seat formed on a bore 84. The valvebody may be a plate or the like instead of ball 83. Please note that thedesign of the cartridge 8 represented in FIG. 7 essentially ischaracterized by rotation symmetry which simplifies manufacture. Bore 84is formed on a front side of cartridge 8 and is axially centered. Bore84 connects the pressure or compression chamber 85 with a channel 86leading to a (non-illustrated) low-pressure accumulator. Ball 84 is heldby a retaining cage 87. A compression spring 89, provided between pumppiston 6 and a retaining ring 88 and essentially arranged withincompression chamber 85, takes care of the required resetting of the pumppiston 6 during operation. Simultaneously, compression spring 89 servesto keep the retaining cage 87, via retaining ring 88, on the bottom ofrecess 90 provided within cartridge 8 and forming compression chamber85. Preferably, the retaining ring 88, however, is also pressed into thecartridge or rather into component 8. While in the example of anembodiment as per FIG. 7 the suction valve is arranged axially on theend of cartridge 8 which is opposite of pump piston 6 the delivery valve81 has an annular plate 92 as closure member. This annular plate 92,e.g., may be a slotted ring of plastic. Plate 92 is prestressed againstcartridge 8 by means of a wire circlip 93 so that, in the closedcondition, delivery valve 81 ensures a pressure medium tightness betweencompression chamber 85 and the channel 94 leading to a pressure mediumconsumer. It is noticed from the representation of FIG. 7 that the valveseat member of cartridge 8 is provided with three clinch-typeconnections or rather caulkings marked by reference mark C forpressure-tight assembly within a pump housing. Please note that theexample of an embodiment of the present invention, represented in FIG.7, is particularly advantageous in that the inside of the valve seatmember of cartridge 8 is designed in a particularlyspace-and-material-saving manner by providing the compression chamber 85which, e.g., may axially be recessed.

Referring to FIGS. 8 and 9, an eighth example of an embodiment of thepresent invention is explained. The eighth example of an embodiment ofthe present invention, represented in FIGS. 8 and 9, in generalresembles the seventh example of an embodiment of the present invention,represented in FIG. 7, yet differs from the same essentially in thatdelivery valve 81 features a modified design. Delivery valve 81 as perFIGS. 8 and 9 includes a valve body preferably designed as a ball 95 andprovided within a radial bore 96 within a section of cartridge 8, facingpump piston 6. This valve body consists of a suitable material,preferably of steel or plastic. Radially outside bore 96, withincartridge 8, a peripheral groove 97 is formed which includes aparticularly conical section 98 in the location of bore 96. A retainingbow 99 acting as a leaf spring serves to prestress ball 95 against itsvalve seat formed by conical section 98. The use of a leaf spring fordelivery valve 81 is possible because of the fact that the openingpressure of delivery valve 81 does not require as accurate an adjustmentas that of suction valve 82. Therefore, no helical spring is needed fordelivery valve 81. Moreover, the opening pressure of the delivery valveis not as decisive as that of the suction valve wherefore the effectivesealing seat diameter may be rated smaller. It is noticed from therepresentation of FIG. 9, in particular, that retaining bow 99,essentially extending over almost the entire periphery of cartridge 8,includes a hole 100 in the location of ball 95. Hole 100 serves to fixball 95 on the valve seat so that, after assembly having been performed,ball 95 cannot slip out of the cartridge unit. Retaining bow 99 ispositively and/or frictionally and operatively fixed on cartridge 8 by,e.g., the caulking C as represented in FIG. 9 in order to prevent bow 99from twisting. Please note that, in accordance with the representationof FIG. 8, the cross-section of bore 84 is larger than that of bore 96which is due to the fact that, when sucking brake fluid, littlethrottling action and hence a larger effective suction cross-section isdesirable for the suction valve 82. As distinguished from the example ofan embodiment described in the context of FIG. 7, the eighth example ofan embodiment of the present invention, represented in FIG. 8, includesa compression spring 101 between the retaining cage 87 which ispreferably made of sheet metal and which also may be referred to asbowl-type spring retainer and ball 83 of suction valve 82. This enablesexact adjustment, i.e., without any great tolerances, of the openingpressure of suction valve 82. Along its inside periphery, retaining cage87 likewise serves to guide compression spring 101. Preferably togetherwith compression spring 101, frictionally held within retaining cage 87,retaining cage 87 is pressed into the valve housing so as to abutthereon. Fixation of retaining cage 87 may alternatively also happen bymeans of one or a plurality of undercuts, provided within the valvehousing or rather within cartridge 8, and by means of catches shaped onretaining cage 87 and (not illustrated) engaging the undercuts. Thesuction valve 82 assembled, retaining cage 87, along its outsideperiphery, likewise serves to guide piston return spring 104. Pistonreturn spring 104 is provided with a stronger resiliency thancompression spring 101 in order to ensure that compression spring 101cannot push retaining cage 87 out. Please note that in the eighthexample of an embodiment of the present invention the various pressurechambers are connected by means of clinching or by means of a“fir-cone-type” connection. Therefore, no separate sealing elements arerequired.

FIGS. 10 and 11 schematically represent a ninth example of an embodimentof the present invention. As distinguished from the eighth example of anembodiment of the present invention explained in the context of FIGS. 8and 9, the retaining bow 99 of the ninth example of the invention doesno longer have any hole. This is an advantage because this renders anytilted position of the ball 95 impossible. By using the retaining bow 99of the ninth example of an embodiment ball 95 is pressed alwaysperpendicularly onto the valve seat formed on bore 96. A bowl-typespring retainer 102 preferably featuring a design characterized byrotation symmetry is arranged in compression chamber 85 and includes anannular, bent-off end portion 103 serving to support one side of thepiston return spring 104. The other side of piston return spring 104abuts on pump piston 6. Bowl-type spring retainer 102 includes a centralaxial bore 105 in order to ensure a flow communication of the pressuremedium between compression chamber 85 and suction valve 82. Preferably,a further means for flow communication of the pressure medium isprovided on the periphery of the bowl-type spring retainer 102 in that,on the periphery, webs are provided in a manner not shown wherebetweenpressure medium can flow. Further, bowl-type spring retainer 102includes an annular recess 106 on its side facing suction valve 82, thisrecess 106 serving to support one side of compression spring 101 of thesuction valve 82. A portion 107 which projects towards the side ofsuction valve 82 and wherein bore 105 is formed and the outside of whichcorresponds to the inside of recess 106 also serves as a stop for thesuction valve body, i.e. for the ball 83. Please note that the bowl-typespring retainer 102 represented in FIG. 10 is made of plastic whichrenders a considerably simplified manufacture as compared with thesheet-metal retaining cage 87 of the example of an embodimentrepresented in FIG. 8. Because of portion 107 of bowl-type springretainer 102 it is impossible for ball 83 to become jammed in theotherwise conically shaped bowl-type spring retainer 102.

A tenth example of an embodiment of the present invention is representedin FIGS. 12 and 13. The tenth example of an embodiment of the presentinvention represented in FIGS. 12 and 13 in particular differs from theeighth and ninth examples of embodiments with regard to the design ofdelivery valve 81. A sheet-metal strip bent to form a clamp 110 isprovided as spring means for pressing ball 95 against the valve seat ofdelivery valve 81. About mid-way, an inventive tongue 111 is worked outof clamp 110. Ball 95 is pressed against its valve seat by means oftongue 111 with a defined force. So as to prevent the clamp 110 fromtwisting, clamp 110 of this embodiment includes two depressed peripheralportions or tabs 112, 113 engaging groove 97. Thus clamp 110 is fixed onthe valve seat member. Further, clamp 110 includes bent ends 114, 115 onboth of its cross sides. These ends facilitate mounting clamp 110 ontothe valve seat member.

Referring to FIGS. 14 through 16, an eleventh example of an embodimentof the present invention is described in the following, with FIG. 16representing a section through FIG. 14 along line XVI—XVI. Asdistinguished from the tenth example of an embodiment of the presentinvention represented in FIGS. 12 and 13, clamp 120 has been widenedconsiderably, it thus extends on the outside of cartridge 8 beyond thegroove 97 towards the eccentric 4. Because of the widening of clamp 120the same is held on cartridge 8 only by its resiliency. Thus no furthermeasures such as welding or caulking are required to fasten clamp 120 oncartridge 8. According to this invention, ball 95 is pressed against itsvalve seat by a tongue 121 formed within the clamp 120. Please note thattongue 121 extends almost over half of the length of clamp 120. A tab123 formed within a recess 122 on the front side of clamp 120 serves tofix clamp 120 on cartridge 8. Please note that, as contrasted with thetenth example of an embodiment, clamp 120 which is embodied in theeleventh example of an embodiment represented in FIGS. 14 through 16 isfixed on cartridge 8 essentially perpendicularly to the resilient actionof retaining clamp 120. Thereby twisting of clamp 120 on cartridge 8 isexcluded to a great extent. Further, according to this invention, theprestressing force of tongue 121 towards ball 95 can be determined moreaccurately. A bore 124 formed within cartridge 8 is provided for tab 123so that the latter can be slipped thereinto and in order to avoid anydisplacement or twisting, respectively, of clamp 121 ²) It can benoticed particularly from the representation of FIGS. 15 and 16 thatclamp 120 extends over half of the periphery of cartridge 8 and,preferably, approximately over two thirds of the periphery of cartridge8. Finally, please note that the suction valve body 125 of the eleventhexample of an embodiment of this invention is shaped like a hammer andthat, on its front side which closure member, it is essentially conicalor spherical, with the valve seat then likewise having a conical orspherical shape. On its opposite front side, the hammer-shaped valvebody 125 preferably includes an annular groove 126 for receiving andguiding compression spring 101 serving as suction valve spring.

LIST OF REFERENCE NUMERALS 1 hydraulic pump or piston pump, respectively2 housing 3 drive shaft 4 eccentric 5 coupling ring 6 pump piston 7 bore8 cartridge or component 9 cap 10 pressure damping chamber 11 deliveryvalve 12 suction valve 13 valve seat member 14 bore 15 section 16section 17 section 18 end portion 19 end portion 20 annular channel 21bore 22 bore 23 chamber 24 retaining ring 25 compression spring 26 valveelement 27 valve element or ball, respectively 28 compression sprig 29plug 30 pin element 31 seal 32 radial bore 33 valve body or ball,respectively 34 compression spring 41 delivery valve 42 suction valve 43valve tappet 44 tension spring 45 bore 46 valve seat member 47 retainingelement 48 closure member 53 valve tappet 54 pin portion 55 end portion56 end portion 57 bore 58 retaining plate 59 outside-periphery portion60 compression spring 61 closure member 62 bore 63 step 64 chamber 70valve seat member 71 gudgeon 72 peripheral groove 73 gasket 74 bore 75compression spring or piston return spring, respectively 76 chamber 77cup-shaped piston 78 bore 79 projection 80 bore 81 delivery valve 82suction valve 83 ball or valve body 84 bore 85 pressure chamber orcompression chamber 86 channel 87 retaining cage or bowl-type springretainer 88 retaining ring 89 compression spring 90 recess 92 plate 93wire circlip 94 channel 95 ball or valve body 96 bore 97 peripheralgroove 98 section 99 retaining bow 100 hole 101 compression spring 102bowl-type spring retainer 103 end portion 104 piston return spring 105bore 106 recess 107 portion 110 clamp 111 tongue 112 peripheral portionor tab 113 peripheral portion or tab 114 end portion 115 end portion 120clamp 121 tongue 122 recess 123 tab 124 bore 125 suction valve body 126annular groove M center line C clinch-type connection or caulking,respectively

What is claimed is:
 1. A piston pump, comprising: a piston, suctionvalve, and delivery valve, wherein the suction valve and the deliveryvalve are preassembled into a component which can be handledindependently, wherein the component is fastened within the housing ofthe piston pump by caulking or clinching, wherein the suction valveincludes a compression spring secured by a bowl-type spring retainer,wherein the bowl-type spring retainer includes a stop thereon providedfor the valve body of the suction valve and with the bowl-type springretainer further including means for guiding the compression spring andmeans for guiding a piston return spring.
 2. A piston pump as claimed inclaim 1, further including one spring element for jointly prestressingthe delivery valve and the suction valve.
 3. A piston pump as claimed inclaim 1, further including a first valve seat for the delivery valve anda second valve seat for the suction valve.
 4. A piston pump as claimedin claim 1, wherein said piston is cup-shaped wherein the componentincludes an axially projecting gudgeon portion guided within thecup-shaped piston.
 5. A piston pump as claimed in claim 1, furtherincluding a valve seat member with an axial recess formed on a frontside thereof wherein the pump piston is guided by the axial recess.
 6. Apiston pump as claimed in claim 5, wherein the suction valve is arrangedessentially coaxially to center line of the valve seat member.
 7. Apiston pump as claimed in claim 6, wherein the delivery valve isarranged essentially radially to the center line of the valve seatmember.
 8. A piston pump as claimed in claim 1, wherein the means forguiding the compression spring and the means for guiding the pistonreturn spring are formed from a cup-shaped portion of the bowl-typespring retainer, wherein the compression spring guided on the inside ofthe cup-shaped portion and wherein the piston return spring is guided onthe outside of the cup-shaped portion.
 9. Piston pump, comprising: apiston a suction valve, and a pressure valve, wherein the suction valveand the pressure valve are integrated into a common component, whereinthe common component is secured in a housing of the piston pump by meansof caulking or clinching and wherein one of the pressure or suctionvalves is arranged substantially axially and the other valve is arrangedsubstantially radially with respect to a center axis of the commoncomponent.
 10. Piston pump according to claim 9, wherein a common springelement is provided for biasing the pressure valve and the suctionvalve.
 11. Piston pump according to claim 9, wherein the commoncomponent includes a valve seat body in which a valve seat for thepressure valve and a valve seat for the suction valve are formed. 12.Piston pump according to claim 9, wherein the pump piston is formed as apot-shaped piston, wherein the common component includes an axiallyprotruding thorn section which is guided in the pot-shaped piston. 13.Piston pump according to claim 9, wherein the common component includesa valve seat body with an axial recess formed on one of its faces, inwhich recess the pump piston is guided.
 14. Piston pump according toclaim 13, wherein the suction valve is arranged substantially coaxiallywith respect to a center axis of the valve seat body on an opposing faceof the valve seat body.
 15. Piston pump according to claim 4, whereinthe pressure valve is arranged substantially radially with respect to acenter axis of the valve seat body.
 16. Piston pump according to claim9, wherein the suction valve has a compression spring which is securedwith a retainer pot, wherein the retainer pot has a shaped-on stop forthe suction valve and wherein the retainer pot also has means forguiding the compression spring and means for guiding a piston returnspring.
 17. Piston pump according to claim 9, wherein the means forguiding the compression spring and the means for guiding the pistonreturn spring are a pot-like section of the retainer pot, wherein thecompression spring is guided on the inside and the piston return springis guided on the outside of the of the pot-like section.
 18. Piston pumpaccording to claim 14, wherein a valve body of the pressure valve isbiased against a valve seat formed on the valve seat body by means of aclamp element securable to the valve seat body, wherein the clampelement has a formed-on tongue which biases the pressure valve bodyagainst the valve seat.
 19. Piston pump according to claim 18, whereinthe clamp element includes a lug for fastening the clamp element on thevalve seat body, which lug is substantially perpendicular to the tongue.20. Piston pump according to claim 18, wherein the clamp element has atleast one lug in parallel with the tongue for fastening the clampelement in a recess for accommodating the valve body in the valve seat.21. Piston pump according to claim 18, wherein the clamp element issignificantly wider than the valve body.
 22. Piston pump according toclaim 18, wherein the clamp element has outwardly arched end sections onits lateral sides.